diff options
| -rw-r--r-- | io.c | 22 |
1 files changed, 21 insertions, 1 deletions
@@ -8493,7 +8493,7 @@ rb_io_advise(int argc, VALUE *argv, VALUE io) * It is not happen for IO-like objects such as OpenSSL::SSL::SSLSocket. * * The best way to use <code>IO.select</code> is invoking it - * after nonblocking methods such as <code>read_nonblock</code>. + * after nonblocking methods such as <code>read_nonblock</code>, <code>write_nonblock</code>, etc. * The methods raises an exception which is extended by * <code>IO::WaitReadable</code> or <code>IO::WaitWritable</code>. * The modules notify how the caller should wait with <code>IO.select</code>. @@ -8555,6 +8555,26 @@ rb_io_advise(int argc, VALUE *argv, VALUE io) * Invoking <code>IO.select</code> before <code>IO#readpartial</code> works well in usual. * However it is not the best way to use <code>IO.select</code>. * + * The writability notified by select(2) doesn't show + * how many bytes writable. + * <code>IO#write</code> method blocks until given whole string is written. + * So, <code>IO#write(two or more bytes)</code> can block after writability is notified by <code>IO.select</code>. + * <code>IO#write_nonblock</code> is required to avoid the blocking. + * + * Blocking write (<code>write</code>) can be emulated using + * <code>write_nonblock</code> and <code>IO.select</code> as follows: + * IO::WaitReadable should also be rescued for SSL renegotiation in <code>OpenSSL::SSL::SSLSocket</code>. + * + * begin + * result = io_like.write_nonblock(string) + * rescue IO::WaitReadable + * IO.select([io_like]) + * retry + * rescue IO::WaitWritable + * IO.select(nil, [io_like]) + * retry + * end + * * === Parameters * read_array:: an array of <code>IO</code> objects that wait until ready for read * write_array:: an array of <code>IO</code> objects that wait until ready for write |